Locking device for the seat posts of chairs



Dec. 9, 1947. c. E. E. LUNDQUIST 3 LOCKING DEVICE FOR THE SEAT POSTS OFCHAIRS Filed May 17, 1945 BY M3? Patented Dec. 9, 1947 LOCKING DEVICEFOR THE SEAT POSTS OF CHAIRS Carl Ernst Edvard Lundquist, Stockholm,Sweden Application May 17, 1945, Serial No. 594,196 In Sweden June 5,1944 Claims.

The invention relates to a device for locking a shaft adapted to bedisplaced in its longitudinal direction relatively to an element. Moreparticularly, the invention relates to a locking device for the seatpost of a chair having a seat to be raised and lowered.

Devices of this kind are known, which consist of a ring provided with ahandle and thrust over the seat post, said ring being rotatably mountedin the frame of the chair and being adapted under the influence of aforce, such as from a spring, to take an oblique position about the seatpost in order to secure the latter to the frame of the chair by aclamping efiect. If the chair seat is loaded, it may occur that thechair post rotates relatively to the clamping ring in spite of theclamping effect thereof, and that an axial displacement of the chairpost thereby takes place. In order to prevent such unintentionalrotation it is known to form the cylindrical chair post with a flatsurface, while the clamping ring is given a corresponding internalshape. It is the object of the invention to improve such a device, sothat the locking effect becomes satisfactory, without it being necessaryto give the shaft or the chair post a shape other than cylindrical.

Further objects and advantages of the invention will be apparent fromthe following description considered in connection with the accompanyingdrawing which forms a part of this specification, and of which:

Fig. 1 shows a portion of a chair having a looking device according tothe invention, the figure being partly represented in vertical section.

Fig. 2 shows a section on the line II-II of Fig. 1.

Fig, 3 shows a somewhat modified construction according to the inventionin a section corresponding to that of Fig. 2.

In the drawing, Ill designates a post or spindle in the form of a tube,the upper end of the spindle carrying a chair seat (not shown). Thespindle i0 is axially displaceable within a sleeve l2 which, togetherwith legs Hi, forms the chair frame resting on a carrying surface.Secured to the frame, preferably the sleeve l2 thereof, as at the lowerportion thereof, is a projection l6 having the locking device accordingto the invention mounted thereon, said locking device consisting of aring [8 arranged about the spindle I3 and of a handle connected to thering. The projection 16, which is preferably of an elongated crosssection in the horizontal plane, is for this purpose provided with arecess 22 on the one side and with a shoulder 24 on the other sidethereof, which enters an elongated aperture 26 in the handle 20. Theelongated aperture 26 is of a length greater than the distance betweenthe bottom of the recess 22 and the shoulder 24, in order to ensure acertain freedom of movement between the ring and the handle on the onehand and the projection on the other hand, in a direction toward andfrom the spindle, while the ring l B and the handle 29 are pivotable inthe vertical direction (in a plane through the longitudinal axis of thespindle). The projection 16 is of greater width below the recess 22 andthe shoulder 24, and forms an abutment 28 for the retention of a platespring 30 hearing with an initial tension on the handle 20 adjacent tothe free end thereof. The spring 30 causes the ring 18 to take anoblique position relative to the spindle IB, that is to say, at arelatively small angle to the horizontal plane. The handle 20 as well asthe spring 30 loosely engage the projection l6, that is to say, theyhave no special securing members.

According to the invention, the ring I8 is formed in such manner as tobear on the spindle I0 in three places at least. In the embodimentaccording to Figs. 1 and 2, the ring I8 is formed on the inside thereofwith two surfaces 34 forming an angle between them, said surfaces then1ying each on one side of a line extending through the centre of thespindle and the centre of the projection l6. Furthermore, the surfaces34 are disposed on that side of the spindle In which is opposed to thehandle 20. When the locking device is in the locking position indicatedby full lines in Figs. 1 and 2, the surfaces 34 have a wedge actionensuring the above-mentioned effect, that is so that the axial positionof the spindle is fixed while a turning movement between the spindle IOand the frame is safely prevented at the same time, even when thespindle carries load. It has been proved in practice that the lockingeffect becomes particularly pronounced Where the spindle is tubular, andparticularly good results are obtained with tubular spindles made fromresilient material, such as steel.

By moving the hindle 20 downwardly according to Fig. 1 about theprojection 16, the ring [8 is caused to move upwardly into a positionwhere it is at least approximately in a plane at right angles to theaxis of the spindle, as indicated by the dash and dot lines in thefigures. The locking engagement between the ring 18 and the spindle Illis thus discontinued, and the spindle may be displaced in itsongitudinal direction. Preferably, the projection It prevents the handlefrom swinging down lower than this substantially horizontal position. Inthe embodiment shown, the handle 20 and the ring l8 are brought intocontact with the shoulder 24 in the position in question. Consequently,the handle 20 cannot be swung down so far that the ring l8 adjustsitself into the corresponding upper clamping position.

While in the embodiment according to Fig. 2 the ring [8 is of a curvedor circular shape at the contact surface against the spindle on the sideopposed to the surfaces 34, the embodiment according to Fig. 3 also hasa two-point bearing on this side. The ring I8 is thus formed withsurfaces 36 symmetrical with respect to the abovementioned line throughthe centre of the projection l6 and the axis of the spindle. Oherwise,the locking device according to Fig. 3 may be constructed in the samemanner as in the preceding embodiment, the same reference charactersbeing used for corresponding parts.

While two more or less specific embodiments of the invention have beenshown, it is to be understood that the same is for purpose ofillustration only, and that the invention is not to be limited thereby.but its scope is to be determined by the appended claims.

What I claim is:

1. In a device of the class described, a supporting structure having acylindrical sleeve, a cylindrical rod axially displaceable in saidsleeve, a member secured to said structure and extending to one side ofsaid rod, a ring encircling said rod, a handle secured to said ring andextending therefrom, said handle being formed with an openingtherethrough, said member extending loosely through said opening andhaving a shoulder for pivotally supporting said handle, a springstressed between said member and said handle for pivoting the latter totilt-said ring with respect to a plane normal to the axis of said rod,and the interior configuration of said ring being non-circular so as toprovide at least three separate points of contact with said cylindricalrod when the ring is tilted.

2. A device as defined in claim 1 in which the rod comprises a hollowtube of resilient material.

3. A device as defined in claim 1 in which the interior of said ringincludes two surfaces arranged at an angle with respect to each otherand disposed on the side of the ring opposite said handle. V

4. A device as defined in claim 1 in which the interior of said ringincludes at least four surfaces, each surface being arranged at an anglewith respect to adjacent surfaces, two of said surfaces being disposedon the side of the ring adjacent to said handleand another two of saidsurfacesbeing disposed on the opposite side of said ring.

5. A device as claimed in claim 1 in which said member is provided withan abutment limiting pivoting of said ring to a plane substantiallynormal to the axis of said rod.

CARL ERNST EDVARD LUNDQUIST.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number

